The CIA is secretly targeting Islamic extremists in Syria for possible lethal drone strikes as part of a contingency plan to protect the US and its allies in the event the turmoil there worsens, current and former US officials say.
President Barack Obama has not authorised drone missile strikes in Syria, and none are under consideration.
But the CIA effort, which involves assembling detailed dossiers on key militants, gives the White House both lethal and non-lethal options if it concludes that Syria's two-year-old civil war - which has already caused 70,000 deaths, according to UN estimates - is creating a new haven for terrorists. The intelligence files also could be used to help moderate opposition figures prevail over extremists.
The Counter Terrorism Centre, which runs the CIA's covert drone killing programme in Pakistan and Yemen, recently shifted several targeting officers to improve intelligence collection on militants in Syria who could pose a terrorist threat, the officials said.
The targeting officers have formed a unit with colleagues who were tracking al-Qaeda operatives and fighters in Iraq. US officials believe that some of these operatives have moved to Syria and joined Islamic militias battling to overthrow President Bashar al-Assad.
The targeting is part of an array of CIA and Pentagon responses and contingency plans as the Syrian bloodletting steadily worsens, threatening regional stability. Other proposals include plans to seize or destroy Syria's chemical weapons stockpiles, which are closely monitored by US intelligence, to prevent their misuse.
The targeting officers focusing on Syria are based at CIA headquarters in Langley, in the state of Virginia, officials said. The agency has not deployed many American operatives into the war zone, but it works closely with Saudi, Jordanian and other regional spy services active there. CIA officers meet Syrian rebel leaders in Turkey and Jordan, current and former officials say.
The increased US effort comes as radicalised Islamic fighters have won a growing share of rebel victories. The State Department says one of the strongest militias, Al Nusra Front, is a terrorist organisation that is indistinguishable from the group al-Qaeda in Iraq.
Amnesty International reported on Thursday that some Syrian opposition fighters routinely executed captives and suspected informants, although the group said Assad's security forces were even more brutal.
At least in public, the White House has limited the US role in the war to sending food and medical supplies to rebels, as well as aid to nearby countries that have taken in nearly a million refugees. US allies are providing weapons and ammunition to the rebels, but Obama has so far objected to proposals for more aggressive US intervention.
CIA targeting officers normally assemble bits of intelligence - including agent reports, mobile phone intercepts, video footage, public records, tips from foreign spy services - to create folders known as "targeting packages", for a variety of reasons.
They can be used if policymakers determine further surveillance, arrest or other action is warranted. The CIA has created non-lethal targeting packages, for example, for drug cartel leaders in Mexico and nuclear scientists in Iran.
Identifying possible threats in Syria would be "a logical step if the policy community sends a signal that, 'Hey, you guys might want to think about how you would respond to a possible request for plans about how you would thin the herd of the future insurgency'", said a former CIA officer with experience in the Middle East.